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comparison: mfbt/RollingMean.h
mfbt/RollingMean.h
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| -1:000000000000 | 0:56b7b8d39557 |
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| 1 /* -*- Mode: C++; tab-w idth: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ | |
| 2 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 3 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 5 | |
| 6 /* A set abstraction for enumeration values. */ | |
| 7 | |
| 8 #ifndef mozilla_RollingMean_h_ | |
| 9 #define mozilla_RollingMean_h_ | |
| 10 | |
| 11 #include "mozilla/Assertions.h" | |
| 12 #include "mozilla/TypeTraits.h" | |
| 13 #include "mozilla/Vector.h" | |
| 14 | |
| 15 #include <algorithm> | |
| 16 #include <stddef.h> | |
| 17 #include <stdint.h> | |
| 18 | |
| 19 namespace mozilla { | |
| 20 | |
| 21 /** | |
| 22 * RollingMean<T> calculates a rolling mean of the values it is given. It | |
| 23 * accumulates the total as values are added and removed. The second type | |
| 24 * argument S specifies the type of the total. This may need to be a bigger | |
| 25 * type in order to maintain that the sum of all values in the average doesn't | |
| 26 * exceed the maximum input value. | |
| 27 * | |
| 28 * WARNING: Float types are not supported due to rounding errors. | |
| 29 */ | |
| 30 template<typename T, typename S> | |
| 31 class RollingMean | |
| 32 { | |
| 33 private: | |
| 34 size_t mInsertIndex; | |
| 35 size_t mMaxValues; | |
| 36 Vector<T> mValues; | |
| 37 S mTotal; | |
| 38 | |
| 39 public: | |
| 40 static_assert(!IsFloatingPoint<T>::value, | |
| 41 "floating-point types are unsupported due to rounding " | |
| 42 "errors"); | |
| 43 | |
| 44 RollingMean(size_t aMaxValues) | |
| 45 : mInsertIndex(0), | |
| 46 mMaxValues(aMaxValues), | |
| 47 mTotal(0) | |
| 48 { | |
| 49 MOZ_ASSERT(aMaxValues > 0); | |
| 50 } | |
| 51 | |
| 52 RollingMean& operator=(RollingMean&& aOther) { | |
| 53 MOZ_ASSERT(this != &aOther, "self-assignment is forbidden"); | |
| 54 this->~RollingMean(); | |
| 55 new(this) RollingMean(aOther.mMaxValues); | |
| 56 mInsertIndex = aOther.mInsertIndex; | |
| 57 mTotal = aOther.mTotal; | |
| 58 mValues.swap(aOther.mValues); | |
| 59 return *this; | |
| 60 } | |
| 61 | |
| 62 /** | |
| 63 * Insert a value into the rolling mean. | |
| 64 */ | |
| 65 bool insert(T aValue) { | |
| 66 MOZ_ASSERT(mValues.length() <= mMaxValues); | |
| 67 | |
| 68 if (mValues.length() == mMaxValues) { | |
| 69 mTotal = mTotal - mValues[mInsertIndex] + aValue; | |
| 70 mValues[mInsertIndex] = aValue; | |
| 71 } else { | |
| 72 if (!mValues.append(aValue)) | |
| 73 return false; | |
| 74 mTotal = mTotal + aValue; | |
| 75 } | |
| 76 | |
| 77 mInsertIndex = (mInsertIndex + 1) % mMaxValues; | |
| 78 return true; | |
| 79 } | |
| 80 | |
| 81 /** | |
| 82 * Calculate the rolling mean. | |
| 83 */ | |
| 84 T mean() { | |
| 85 MOZ_ASSERT(!empty()); | |
| 86 return T(mTotal / mValues.length()); | |
| 87 } | |
| 88 | |
| 89 bool empty() { | |
| 90 return mValues.empty(); | |
| 91 } | |
| 92 | |
| 93 /** | |
| 94 * Remove all values from the rolling mean. | |
| 95 */ | |
| 96 void clear() { | |
| 97 mValues.clear(); | |
| 98 mInsertIndex = 0; | |
| 99 mTotal = T(0); | |
| 100 } | |
| 101 | |
| 102 size_t maxValues() { | |
| 103 return mMaxValues; | |
| 104 } | |
| 105 }; | |
| 106 | |
| 107 } // namespace mozilla | |
| 108 | |
| 109 #endif // mozilla_RollingMean_h_ |
